Ubuntu 14.04 and USB to Serial ch341 (chinese device from Ebay)

You can find pretty cheap USB to Serial devices on Ebay. I bought one and received a device using a chip ch341.

Unfortunately, the drive is bugged in Ubuntu 12.04 and 14.04. Fortunately, there is patch to fix it.

Here is how to recompile the module to enjoy these devices.

$ sudo apt-get source linux-source-3.13.0 linux-headers-$(uname -r)
$ cd /tmp
$ tar -xjf /usr/src/linux-source-3.13.0.tar.bz2
$ cd linux-source-3.13.0/
$ make oldconfig
$ make prepare
$ make scripts
$ cp -v /usr/src/linux-headers-$(uname -r)/Module.symvers .
$ cp /lib/modules/$(uname -r)/kernel/drivers/usb/serial/ch341.ko /lib/modules/$(uname -r)/kernel/drivers/usb/serial/ch341.ko.orig
$ cd drivers/usb/serial
$ cp ch341.c ch341.c.orig
$ wget https://github.com/karlp/ch341-linux/raw/master/0001-usb-serial-ch341-Add-parity-support.patch
$ cat 0001-usb-serial-ch341-Add-parity-support.patch | patch -p4
patching file ch341.c
Hunk #1 succeeded at 349 (offset 3 lines).
Hunk #2 succeeded at 370 (offset 3 lines).
$ make -C /lib/modules/$(uname -r)/build M=$(pwd) modules
$ sudo cp ch341.ko /lib/modules/$(uname -r)/kernel/drivers/usb/serial/ch341.ko
$ sudo rmmod ch341
$ sudo modprobe ch341 

Source for instructions: http://askubuntu.com/questions/515407/how-recipe-to-build-only-one-kernel-module